Damborg Peter, Moodley Arshnee, Aalbæk Bent, Ventrella Gianpiero, Dos Santos Teresa Pires, Guardabassi Luca
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark.
Department of Veterinary Medicine, Università degli Studi di Bari, Strada P.le per Casamassima Km 3, Valenzano-Bari, 70010, Italy.
BMC Vet Res. 2016 Jun 29;12(1):131. doi: 10.1186/s12917-016-0756-y.
Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged globally in companion animals in the last decade. In Europe, the multidrug-resistant sequence type (ST)71 is widespread, but recently other clones have appeared. The objective of this study was to examine genotypic diversity and antimicrobial resistance of clinical MRSP isolates obtained from dogs, including dogs sampled on multiple occasions, in Denmark over a six-year period. For that purpose a total of 46 clinical MRSP isolates obtained from 36 dogs between 2009 and 2014 were subjected to antimicrobial susceptibility testing, multilocus-sequence typing (MLST) and SCCmec typing.
Twenty-three sequence types were identified with ST71, mostly associated with SCCmec II-III, as the most common occurring in 13 dogs. Among the remaining 33 isolates, 19 belonged to clonal complex (CC)258 comprising ST258-SCCmec IV and its single- and double-locus variants. These were susceptible to 4-7 of the 22 antibiotics tested, whereas CC71 isolates were susceptible to only 2-5 antibiotics. Clone-specific differences were especially pronounced for fluoroquinolones and aminoglycosides with most CC71 isolates being resistant and almost all CC258 isolates being susceptible. Sixteen of the 19 CC258 isolates had oxacillin MICs of 0.5 g/L, whereas MICs for CC71 isolates were consistently above 4 g/L. Four of five dogs representing multiple isolates had distinct STs on different sampling events.
The overall genotypic diversity of MRSP is high in Denmark indicating multiple acquisitions of SCCmec into distinct clones, and mutational evolution, which appears to be particularly rapid for certain ancestral clones such as ST258. ST71-SCCmec II-III is the most common MRSP lineage and is typically multidrug-resistant. CC258-SCCmec IV isolates, which emerged in Denmark since 2012, display susceptibility to a wider range of antimicrobials. The isolation of distinct STs in individual dogs over time suggests repeated exposure or short-term genetic evolution of MRSP clones within patients.
耐甲氧西林中间型葡萄球菌（MRSP）在过去十年中已在全球范围内的伴侣动物中出现。在欧洲，多重耐药序列类型（ST）71广泛存在，但最近出现了其他克隆。本研究的目的是检测从丹麦的犬类中获得的临床MRSP分离株的基因型多样性和抗菌药物耐药性，其中包括多次采样的犬只，研究为期六年。为此，对2009年至2014年间从36只犬中获得的46株临床MRSP分离株进行了抗菌药物敏感性测试、多位点序列分型（MLST）和SCCmec分型。
共鉴定出23种序列类型，其中ST71最为常见，在13只犬中出现，大多与SCCmec II-III相关。在其余33株分离株中，19株属于克隆复合体（CC）258，包括ST258-SCCmec IV及其单一位点和双位点变体。这些分离株对22种测试抗生素中的4至7种敏感，而CC71分离株仅对2至5种抗生素敏感。克隆特异性差异在氟喹诺酮类和氨基糖苷类药物中尤为明显，大多数CC71分离株耐药，而几乎所有CC258分离株敏感。19株CC258分离株中有16株的苯唑西林MIC为0.5 g/L，而CC71分离株的MIC始终高于4 g/L。代表多个分离株的5只犬中有4只在不同采样事件中具有不同的ST。
丹麦MRSP的总体基因型多样性较高，表明SCCmec多次进入不同克隆，并发生了突变进化，对于某些祖先克隆如ST258而言，这种进化似乎特别迅速。ST71-SCCmec II-III是最常见的MRSP谱系，通常具有多重耐药性。2012年以来在丹麦出现的CC258-SCCmec IV分离株对更广泛的抗菌药物敏感。随着时间的推移，在个体犬中分离出不同的ST，提示患者体内MRSP克隆存在反复暴露或短期遗传进化。
